Format: 

Lastname, Firstname. "Title of Paper." Title of Proceedings, Publisher, Date of Publication, Page(s). Database Name or Title of Non-Publisher Website, DOI or URL

Lastname, Firstname. "Title of Paper." Title of Proceedings, Publisher, Date of Publication, Page(s), URL or DOI (when accessed from the publisher's website).

Lastname, Firstname. "Title of Paper." Title of Session. Title of Conference, Month Day Year, Venue, City.L

Examples: 

Oram, Denise. "Considering Sustainability Through Ethical Approaches and Their Practical Application." IEEE International Symposium on Technology and Society, 18-20 May 2009. Tempe: IEEE, 2009. 1-6. IEEE Xplore. Web. 15 July 2015.

In-text: (Oram 2)

Oram, Denise. "Considering Sustainability Through Ethical Approaches and Their Practical Application." Proceedings of the 2009 IEEE International Symposium on Sustainable Systems & Technology (ISSST) and 2009 IEEE International Symposium on Technology and Society (ISTAS): May 18-20, 2009, Tempe, Arizona, IEEE, 2009, pp. 1-6. IEEE Xplore, doi:10.1109/ISTAS.2009.5155906.

In-text: (Oram 2)

Notes: 

For a live presentation, include the location of the conference including the name of the venue. If the city is part of the venue's name, omit the city (MLA 50). If the conference paper is published in a conference proceeding, cite it as you would a book chapter (see second example). If the conference paper is published as a standalone document in an institutional repository or on a professional website, use the format for a live presentation, but include the web address at the end. For help structuring the title of the conference, see MLA 70.

Source:
MLA - p. 50